The present disclosure relates to particulate dispensing methods and apparatus for providing the same. In particular, the present disclosure provides for improving traveling wave grids and the electrodes therein to improve the movement and control of organic, inorganic and/or biological particles being carried.
Traveling wave grids are known in the art. See, for example, U.S. Pat. Nos. 6,351,623; 6,290,341; and 7,304,258. As explained in these documents, a traveling wave grid may, as shown in FIG. 1, be a single sided traveling wave grid device 100, such as an electrostatic traveling wave grid, comprising a plate 110, a plurality of parallel and closely spaced electrodes 112, 114, 116, and 118, and an effective amount of a carrier medium 120, of liquid or gel disposed in communication with the electrodes. In one design, the electrodes may be formed from platinum or alloys thereof. A thin layer of titanium may be deposited as a pattern on the plate, which may be glass, to form the e electrodes. A four phase electrical signal (Φ1-Φ4) is shown as being utilized in conjunction with assembly 100 where the phases are 90° apart. In general, there may ne n phases which are 360°/n apart. Accordingly, a first electrode such as electrode 112 may be utilized for a first phase Φ1 of the electrical signal. Similarly, a second electrode immediately adjacent to the first, such as electrode 114, may be utilized for a second phase Φ2 of the electrical signal. Additionally, a third electrode immediately adjacent to the second electrode, such as electrode 116, may be utilized for a third phase Φ3 of the electrical signal. Moreover, a fourth electrode immediately adjacent to the third electrode, such as electrode 118, may be utilized for a fourth phase Φ4 of the electrical signal. The distance between the centers of adjacent electrodes is referred to as pitch, and denoted as “p.” The width of an electrode is denoted as “w,” while the distance between facing sidewalls or edges of adjacent electrodes is “s.” Further, as appreciated by one of ordinary skill in the art, the above concepts may be used to form a double sided grid assembly, which employs a second design similar to that as described and located so that the two surfaces are on either side of the carrier medium.
FIG. 2 is a schematic illustration of an electrophoretic traveling wave grid system (device) 200 utilizing multiple distributed, reconfigurable, and reprogrammable traveling wave grids. Specifically, the traveling wave grid system includes multiple grid segments, such as a first grid segment 210, a second grid segment 220, and a third grid segment 230. As will be appreciated, each segment includes a plurality of substantially parallel and proximately spaced electrodes. One or more buses 240, 250, and 260 can provide coupling to the four phase grid circuit. The system 200 further comprises one or more programmable voltage controllers, such as controllers A, B, and C. A sample 270 (of bio-material or other type of particles, e.g., toner particles) can be deposited onto the grid segment 210. The sample migrates to region 272 and continues to migrate onto adjacent grid segment 220, for example. Operation of system 200 continues until a region 274 of bio-molecules may form within grid 220. Depending upon the bio-molecules and grid parameters, the particles constituting region 274 may further migrate to adjacent grid segment 230, and form a region 276 of particles.
Presently, such traveling wave grids are formed through traditional semiconductor fabrication techniques (e.g., photo masking, metallization, etching, etc.).
Employing such fabrication techniques results in high manufacturing costs and a device which is not reconfigurable, i.e., the physical structure is permanent so the placement of the electrodes cannot be altered. Therefore, when another grid pattern is required, the fabrication process must again be undertaken. This is seen as a drawback in the art.
Another particle manipulation technique is discussed in an article by P. Y. Chiou, A. T. Ohta and M. C. Wu, entitled, “Massively Parallel Manipulation of Single Cells and Microparticles Using Optical Images”, Nature, 436, July (2005), which was directed to precise manipulation of single microparticles in an active area of 1 mm×1 mm, by use of optical tweezers.